Re: profiling question

On 12 Aug 2007, at 12:26, Vangelis Katsikaros wrote:
> In http://dev.mysql.com/doc/refman/5.0/en/server-system-variables.html
> "profiling" and "profiling_history_size" variables are noted as
> session variables, which is also mentioned in
> http://dev.mysql.com/doc/refman/5.0/en/show-profiles.html
>
> However profiling_history_size can be set from the my.cnf file
> where as
> profiling can't. Also from mysql command line it is possible to do ie
> SET GLOBAL profiling_history_size=10;
>
> So is profiling_history_size session but handled like global or simply
> hasn't been updated in the docs?

The session's history-size is set from the global size when the session is created. You may think of it as a default value.

> Also I would like to ask if there is a reason for not having
> profiling as global variable.

Yes, it's intentional.

Profiling is expensive, and it should never be left on. This is a safeguard against our users who don't read the manual.

Furthermore, profiling data is session-specific. Outside of a session, there's no way to access the profiling data. Thus, it doesn't make sense to enable profiling from outside, when one can't access it from outside.

Now, it would be nice to create a way to write "remote" profiling data to a table. Say, I'm in connection 23 and I want profiling data on connection 42 (or some expression that describes the session), it would be nice to turn on profiling and write its results to a particular table that I name. I invite that feature to be implemented.

• chad

--
Chad Miller, Software Developer                         chad@mysql.com
MySQL Inc., www.mysql.com
Orlando, Florida, USA                                13-20z,  UTC-0400
Office: +1 408 213 6740                         sip:6740@sip.mysql.com


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